The invention relates to means for heating fuel used in operation of a diesel engine, and in particular to the provision of such heating both during operation of the engine and in periods between successive uses of the engine.
In colder climates, diesel operation has encountered a problem attributable to formation of wax crystals, due to paraffin content of the fuel. For reasons of economy, No. 2 fuel oil is desired, but this grade is afflicted with the wax problem, which can be as severe as to clog the filter system, located prior to the injector pump, thus starving the engine of fuel. To avoid the problem, No. 1 fuel (kerosene) has been recommended, but the incremental cost per gallon is not palatable. The other answer to the problem is to provide means for heating the fuel.
To my knowledge, prior and existing fuel heaters associated with diesel engines, such as truck engines, farm-tractor engines and the like have employed a shell and tube heat-exchanger arrangement wherein fuel on its way from the tank to the fuel-injection system of the engine is coursed through the tube or tubes, while a flow of the liquid coolant used to remove engine heat is coursed through the shell, in heat-transfer relation with the flow of fuel to the injection system. In such an arrangement, the fuel is warmed only if the engine has been run long enough to sufficiently warm the flow of engine coolant, and the only fuel that is warmed is that which is on its way directly to the fuel-injection system of the engine.
Also, to my knowledge, for colder climates and to ease the problem of start-up after engine shut-down, for example after an overnight shut-down, the practice is to install an engine-block heater element, adapted for selective and detachable connection to an external source of electric power. But this practice provides little or no heating of the fuel that is supplied or is to be supplied to the fuel-injection system of the engine.